Six pairs of parents from a kindergarten took six children to participate in a parent-child tour group. The registration fee for each adult was 400 yuan, half price for children, and the group purchase price was 300 yuan per person.

A: All sign up individually, 6 pairs of parents and 12 people: 12×400=4800, 6 children: 6×200=1200; add up = 6000; B: All group purchases, 12 parents + 6 children=18 people, 18×300

=5400C: Group purchase for 12 parents: 12×300=3600, half price for 6 children, 6×200=1200, total = 4800; so plan C is the best and most economical